1. Field of the Invention
The present invention relates to an ink jet recording apparatus and an operating method thereof and, more particularly, to an ink jet recorder and an operating method of an ink jet recording apparatus for preventing poor ink discharge from an ink discharge port of a recording head.
2. Related Background Art
An ink jet recording apparatus supplies ink in a recording head, and a drive element or elements (i.e., an electrical-thermal energy converter, e.g., a heat generating element or an electric-mechanical energy converter, e.g., a piezoelectric element) corresponding to one or a plurality of ink discharge ports, formed in the front surface of the recording head are driven in accordance with a data signal, thereby discharging ink from the ink discharge port as ink droplets toward a recording medium (recording paper) to record an image.
In the ink jet recording apparatus of this type, a capping operation is performed for capping the ink discharge ports with a cap while not printing and a recovery operation for restoring the discharge function, e.g., a predetermined idle discharge, for discharging ink away from a printing area is sometimes carried out. This prevents the ink discharge ports from clogging caused by an increase in viscosity of ink due to evaporation of an ink solvent or ingestion of dust or mixture of bubbles and stabilizes printing quality.
Conventionally, an operator visually judges the printing quality and carries out the recovery operation in accordance with the judgment. However, it is difficult to judge whether or not the recovery operation is absolutely necessary.
In addition, it is difficult to always maintain a stable, objectively good ink discharge condition if the recovery operation is performed only when the operator subjectively judges it necessary.
If no print command is supplied for a predetermined period of time, the ink discharge portion is dried, and its initial discharge characteristic is degraded, resulting in unstable ink discharge. This problem is particularly noticeable when ink having a high dye concentration is used.
U.S. Pat. No. 3,925,789 discloses a continuous type ink jet recording apparatus which performs ink ejection from a nozzle prior to the next printing operation when the interval between ink injection commands becomes a predetermined interval after the apparatus is powered on and is in the print waiting state.
However, if such ejection is repeated excessively, the amount of waste ink is undesirably increased. In the case that the recording head has a plurality of ink discharge ports, some of the ink discharge ports may not have been used for a long period of time, and the portion of the discharge ports may be dried, resulting in unstable ink discharge.
Further, even if ink is discharged from the ink discharge port into the cap, the ink collected in the cap by the discharge over-flow and the overflow ink may contaminate the ink jet recording apparatus.